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Scheme for Reducing Decoherence in Quantum Computer Memory by Transformation to the Coherence-Preserving States
DUAN Lu-ming, GUO Guang-can
Chin. Phys. Lett. 1997, 14 (7):
488-491
.
If quantum bits (qubits) couple to the Same environment, it has been found the qubits decohere coherently. An interesting result from this phenomenon is that, for a kind of input states, i. e., the coherence-preserving states, coherence of the qubits can be preserved perfectly in quantum memory. In this paper, we propose a feasible scheme to transform an arbitrary unknown input state to the corresponding coherence-preserving state. The transformed state undergoes no decoherence in the noisy memory and, after that, it can be transformed back into the original state with decoherence much reduced. This scheme involves the use of an analogy of the ideas of quantum teleportation.
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A New Determination of 208Hg Half-Life
ZHANG Li, ZHAO Jin-hua, ZHENG Ji-wen, WANG Ji-cheng, YANG Yong-feng, QIN Zhi, GUO Tian-rui
Chin. Phys. Lett. 1997, 14 (7):
507-509
.
A specific detection system devoted to the detection of weak γ-activities from neutron-rich isotopes in an element-separated source was developed, and successfully used in a new determination of the half-life of the recently identified heavy neutron-rich nuclide 208Hg. This newly measured half-life is 41+5-4min, in agreement with the earlier one of 42+23-11 min obtained by radiochemical milking method, but experimental precision was improved.
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Characterization of High-Energy-Heavy-Ion-Induced Defects in GaAs by Positron Annihilation
ZHU Sheng-yun, LUO Qi, FAN Zhi-guo, WANG Chun-rui, ZHENG Sheng-nan, GOU Zhen-hui, LI An-li, QIAN Jia-yu
Chin. Phys. Lett. 1997, 14 (7):
535-537
.
The defects induced by 64 MeV 19F ion irradiation to a Auence of 4.3 ×1016/cm2 are investigated in GaAs by positron annihilation lifetime technique. Di-vacancies are created by the irradiation. The formation of tri- and quadri-vacancies is observed during thermal annealing. The di-, tri-and quadri-vacancies are annealed away at 350, 550 and 800°C, respectively.
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Electronic Structure of Equilibrium-State TiNx Films
ZHANG Zhi-peng, SHEN Yao-wen, XU Wei, HUANG Mei-chun
Chin. Phys. Lett. 1997, 14 (7):
542-545
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By using LMTO-ASA method and supercell approach, the self-consistent band structures for α-Ti, ε-Ti2N, and δ-TiN have been calculated. Moreover, α-Ti, ε-Ti2N, and δ-TiN were taken as three samples corresponding to TiNx films for x = 0, 0.5, 1.0. Then, according to the phase diagram of Ti-N and statistical supercell method, we have, for the first time to our knowledge, calculated the electronic structures of equilibrium-state TiNx films for all compositions of x < 1.0.
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Highly Oriented HgBaCaCuO Superconducting Thin Films Prepared by Laser Ablation
YU Yang, SHAO Hui-min, ZENG Zhao-yang, SUN Ai-min, QIN Meng-jun, REN Chong, XU Xiao-nong, DING Shi-ying, JIN Xin, YAO Xi-xian, ZHOU Jun, JI Zheng-ming, YANG Sheng-zu, ZHANG Wen-lan
Chin. Phys. Lett. 1997, 14 (7):
546-548
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Pb-doped HgBa2CaCu2Oy films were prepared on the (100) SrTiO3 substrate by using laser ablation followed by post-Hg-vapor annealing. These films are dominated by c-axis-oriented Hg-1212 phase as indicated by x-ray diffraction and electromagnetic measurements. The transition temperature Tc0 is 110 K. The critical current density Jc achieved 106 A/cm2 at 77K and zero applied field.
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22 articles
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